Masticating and dispersing blade



April 1931- E. SCHMIERER 1,801,025

MASTICATING AND DISPERSING BLADE Filed Feb. 4, 1950 INVENT 01? E U GENE S CHM/13132 Patented Apr. 14, 1931 UNITED STATES PATENT OFFICE EUGENE SGBIIEREB, OF SAGINAW, MICHIGAN, ASSIGNOR 'IO BAKER PERKINS COM- PANY, INC., 01 SAGINAW, MICHIGAN, A CORPORATION OF NEW YORK 'MASTICATING AND DISPERSING BLADE Application filed February 4, 1930. Serial No. 425,877.

This invention relates to masticating and dispersing machines and pertains more, particularly to cylindric trough mixers equipped with revolving blades and adapted in oper- 5 ation to convert gummy tough elastic substances, such as rubber, into fluid or pasty form, plastic and non-elastic.

A primary object of the invention is to provide a machine of the cylindric trough type that shall be capable of more thoroughly and rapidly converting raw material, consisting of crude or plasticized rubber, water, and a suitable dispersing agent, such as soda, into a fluid, or into a semi-fluid whose particles are so small that the prod not is practicall an emulsion. Another object is to masticate the raw material and to attain thorough dispersion of it at one operation.

Another object is to attain a novel relationship of the rotating blade with the saddle of the trough whereby the blade and saddle cooperate to produce a more efiective action P of the material during the first or disintegrating state of the operation.

The means for attaining these new and useful results is set forth in the appended claims and consists in a certain novel contour or formation of the working face of the mixing blade or rotating element.

With the foregoing and certain other objects in view, which will appear later in the specification, the invention comprises the devices described and claimed and the equivalents thereof.

In the drawings Fig. 1 is a side view of a typical rotatable dispersion blade of the kind to which my invention is applicable.

Fig. 1a is a similar view of a blade to which my invention is applied, for dispersing and also masticating rubber.

Fig. 2 is a part diagrammatic transverse enlarged sectional View on line 2-2 of Fig. 0 1, through a mixer embodying the invention.

Fig. 3 is a transverse section on line 3-3 of Fig. 1a, showing the relationship between the working face of the blade and the inner face and saddle of the mixing bowl. 5a The mixing blade shown in Fig. 1 is of the usual dispersion type and the trough in which it operates is also of the general design customarily employed for disintegrating or mast1cat1ng, as indicated in Fig. 3.

As stated, the present improvement is found in a new form and a novel co-operative relationship between the advancing or workng face of the blade and the cylindric working face of the trough.

An exceedingly important departure from the usual practice is in respect to the contour of the working face of the blade for it 1s by this departure that new, useful and valuable results are attained.

For example, a batch of crude material of given size can be completely converted by mastioating and dispersing, in a machine having my improved form of blade, in about one and one half hours, Whereas in a machine holding the same amount of material and dentlcal 1n design except as to the aforesaid lmproved working face of the blade, from five to eight hours was required to make a disperslon and sometimes it was impossible to properly disperse the material, no matter how long the machine was run.

My present improvement will be understood by reference to Fig. 2 which represents a typical dispersion blade of the type shown in Fig. 1, although it will be understood that the same working face can also be applied by atypical masticator blade, such as shown in Figs. 1a and 3.

The active or front face of the blade com prises three cones, A, B, C of which A designates the primary material agitating or impelling zone that operates to stir the material and urge it outwardly toward the bed of the trough, in known manner.

B is that part of the working face which urges the material gradually against the trough bed, and there rolls, presses and crushes it, the rolling, pressing and crushing action increasing in intensity as the material is brought nearer and nearer to the part 0 of the blade face which is concentric with the cylindrical face of the bowl D.

Zone B is defined by a curve that approaches concentricity with the arc of the trough D, at the placewvhere it is nearest the trough. For the purpose of description it will be assumed that a radius R of the trou h D sweeps from left to right in Fig. 2. it any given position of radius B it intersects the arc of bowl D and the curve of zone B at T, T respectively. Tangents drawn to the curves at thosepoints subtend an angle a, and as radius R sweeps to the right such tangents present decreasing angles. Where zone A merges into zone B the tangent to the blade surface and a tangent to the trough curve subtend an angle of about twenty-five degrees, this being substantially the widest angle at which the working surface of the blade will tend to ride over and roll the rubber against the trough instead of pushing it ahead of the blade. This maximum angle has been arrived at by observation of the machine in actual use.

The curvature of the working face of zone B may be conveniently defined by the arc of a circle drawn with a radius 1" less than the radius of the trough, giving an angularity that varies at a uniform rate. Face B may, if desired, be a curve the length of whose radius increases as the radius swings from zone A around to zone C. 7

Where zone B joins zone C, which constitutes the portion of the blade surface nearest the bowl face, the two curves have a common tangent at their junction S.

Zone C presents a working face of considerable arcuate length and this working face is concentric, or substantially so, with the curve of the working face of the trough D. Between these two concentric faces the material is constrained in the form of a thin film. The amount of clearance between the two working faces at zone C is approximately one sixty-fourth inch. The arcuate length of zone C may in such case be one half to one inch. These proportions may be varied according to circumstances and the results desired to be produced, but the proportions named have in practice been found to be satisfactory for the masticating and dispersion of crude rubber. The arcuate length of zone C and the clearance between the two concentric surfaces is such that there is attained what may be termed a filmshearing action. to be described later.

The operation of the blade is as follows: As the blade travels in the direction of the arrow in Fig. 2 the material is pushed outwardly by zone A of the blade toward the wall of the bowl until it encounters a place on zone B presenting an entrance angle with the trough D such that the material begins to roll upon the surface of the trough. As the blade continues to advance it exerts increas ing pressure on the rolling material because of the constantly decreasing clearance between the working faces of the blade and the bowl. Eventually the material is powerfully crushed against the trough bed. This occurs before zone B ends and while C a'pproaches.

The effect of the diminishing an larity of the working surfaces is to 0 set or counteract the tendency of the material to be squeezed out from between the surfaces, which tendency increases with the increasing pressure. In this way a large part of the material that initially comes into contact with the blade is sure to be forced under the blade giving the machine great hourl production capacity as com ared with ormer devices wherein the ang e of approach of the surfaces was so wide that the blade tended to push the material ahead of it, instead of riding upon and over it.

The material is in a state of high internal pressure by the time it is between the zone C of the blade face and the wall D of the trough.

One side of the film of material in the space between these close concentric working faces adheres to the working face of zone C on the blade and the other side of the fihn adheres to the face D of the bowl. The areas of adhesion, on account of the arcuate length of zone C, are relatively extensive, presenting large surfaces, One stationary, the other moving. The proportion of arcuate length to clearance is such that the material instead of merely being spread on the trough, as by the narrow tip commonly provided on former blades, the intervening film of material is disrupted. Since the adhesion of the material to the relatively moving surfaces is greater than the cohesion of the particles, the outside layers of the film are moved past each other. The resultant film-shearing effect disrupts the globules of rubber within the film and exposes new surfaces of material to the protective or separating action of the water or other dispersing medium. In practice a machine having an arcuate length in zone 0 one half inch and a clearance of one thirty second to one sixty fourth inch gives satisfactory results.

High internal pressure produced in the film by my improved blade makes the shearing action more effective and forces the dispersing medium into intimate contact with the freshly divided globules of rubber that are produced by the shearing action. Moreover, the high pressure increases the frictional adhesion of the material to the relatively moving surfaces of the blade and trough.

where it is used for mastication alone because 4 the working face comprising zones B and G presents no sharp edges or ridges and conseqwintly has no cutting action on the materia 8 When masticating solid rubber the blade herein shown serves a useful purpose in conjunction with a trough saddle having a rounded ridge. The rounded working face 30 of the blade co-operates with the rounded ridge 4, shown in Fig. 3, to break down the resilience of the rubber by repeated stretching beyond its elastic limit and then pulling it apart. This eflfects a marked improvement s over the cutting action of former machines wherein the saddle ridge is sharp, and the tip of the blade is also sharp. Elasticity is most effectively destroyed by repeated stretching beyond the elastic limit, followed by 20' breaking, as distinguished from shearing and beiiting, and my improvement gives this resu t.

My invention makes it possible to use a single machine to break up, plasticize, and

; disperse crude rubber in one operation, as distinguished from prior practice wherein the material was broken down between power driven rolls or in an old style masticator' and then transferred to another machine, such as 30 a colloid mill, for dispersing.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: l. A machine for treating rubber and other heavy plastic materials having a cylindrical trough, a rotor coaxially mounted within said trough whose working face throughout its length, in section perpendicular to the rotor axis, comprises three successive zones name- 4 ly, a zone concentric with said trough, of

such width relative to its clearance from the trough surface that a film-shearing action is produced in the material between the surfaces, a second zone joined substantially tan-' gentially to said concentric zone and extending axially inward from the trough surface in a curve increasingly inclined to the arc of the trough, such inclination measured between tangents drawn to the curve and arc 59 at their points of intersection with a moving radius of said arc, said curve continuing at least to the point where said tangents form an angle of twenty five degrees, and a material-lmpelling zone joined to said second zone.

2. A combination as claimed in claim 1 wherein the trou h comprises a plurality of parallel intersectmg'cylindrical surfaces, any two of which at their intersection form a saddle,and a rounded ridge on said saddle ada ted to coerate with the working face of t e rotor, su stantiall as described.

In testimony whereof, afiix my si ature.

-EUGENE SCHMIE ER.

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